This invention relates to supports for tooling for use with lathes, and more particularly to tool posts.
Tool posts are devices that are adapted to be mounted on machine tool beds or compounds of lathes or other machine tools to support tool holders. The tool holders in turn hold the tools which actually work on the workpiece. Tool posts have been provided with a main body having on two sides horizontally-projecting tongues or mounts in a dovetail configuration. Tool holders are provided with a mating slot so as to permit the tool holders to be mounted on the dovetail mounts. A tool post and tool holder with this type of configuration is shown for example, in U.S. Pat. No. 2,972,272 of Sirola.
Tool holders are engaged on the sides of the tool posts by wedge-shaped gibs that form one surface of the dovetail-shaped tongue. The wedge-shaped gibs are integrated with a cam follower surface that is adapted to be engaged by a helical cam surface on a vertical screw in the center of the tool post body block. By turning a handle mounted on the screw, the gibs are moved vertically to lock and unlock the tool holders from the dovetail mounts.
The inventor has noted a variety of disadvantages associated with prior art designs of tool posts with dovetail mounts. The tool posts are prone to rotation with respect to the compound on the lathe, as only friction between the bottom surface of the body block and the top surface of the compound of the lathe holds the body block in place. The tool holders cannot be indexed and cannot be selectively removed and added. This results in periods of time when the tool post, and as a result the lathe on which it is mounted, is out of service while tool holders are changed. Accurate indexing and rotation of the tool post requires moving of the body block relative to an index plate. Tool posts of the prior art have very limited options as to the height of the tool holders on the tool posts.